Why is Friday the 13th Considered Unlucky?

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Today, people around the globe will feel uneasy about getting out of bed, leaving their homes, or going about their normal daily routines, all because of a superstition. These unfortunate folks suffer from paraskavedekatriaphobia, a common neurosis familiar to us all: the fear of Friday the 13th. But just where did this superstitious association come from, and how did it catch on?

The truth is that no one is absolutely sure where the idea that Friday the 13th is unlucky originated. Donald Dossey, the founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina, suspects the fear can be traced back to a Norse myth about 12 gods who had a dinner at Valhalla—the fabled hall where legendary Norse heroes feasted for eternity after they died—that was interrupted by a 13th guest, the evil and mischievous god Loki.

According to legend, Loki tricked Höðr (the blind god of winter and son of Odin, the supreme god in Norse mythology) into shooting his brother Baldr (the benevolent god of summer who was also a son of Odin) with a magical spear tipped with mistletoe—the only substance that could defeat him. Thus the number 13 was branded as unlucky because of the ominous period of mourning following the loss of such powerful gods by this unwanted 13th guest.

For whatever reason, among many cultures, the number 12 emerged throughout history as a "complete" number: There are 12 months in a year, 12 signs of the zodiac, 12 Gods of Olympus, 12 sons of Odin, 12 labors of Hercules, 12 Jyotirlingas or Hindu shrines where Shiva is worshipped, 12 successors of Muhammad in Shia Islam, and 12 tribes of Israel. In Christianity, Jesus was betrayed by one of his 12 Apostles—Judas—who was the 13th guest to arrive for the Last Supper. Surpassing the number 12 ostensibly unbalances the ideal nature of things; because it is seen as irregular and disrespectful of a sense of perfection, the number 13 bears the stigma of misfortune and bad luck we know today.

WHY FRIDAY?

Friday joins in the mix mostly because all of the early accounts of Jesus’s crucifixion agree that it took place on Friday—the standard day for crucifixions in Rome. As Chaucer noted in The Canterbury Tales, "And on a Friday fell all this mischance." Yet perpetuating Friday as an unlucky day in America came from the late 19th-century American tradition of holding all executions on Fridays; Friday the 13th became the unluckiest of days simply because it combined two distinct superstitions into one. According to the Oxford University Press Dictionary of Superstitions, the first reference to Friday the 13th itself wasn’t until 1913. (So despite actually occurring on Friday, October 13, 1307, the popular notion that the Friday the 13th stigma comes from the date on which the famed order of the Knights Templar were wiped out by King Philip of France is just a coincidence.)

The repercussions of these phobias reverberated through American culture, particularly in the 20th century. Most skyscrapers and hotels lack a 13th floor, which specifically comes from the tendency in the early 1900s for buildings in New York City to omit the unlucky number (though the Empire State Building has a 13th floor). Some street addresses also skip from 12 to 14, while airports may skip the 13th gate. Allegedly, the popular Friday the 13th films were so-named just to cash in on this menacing date recognition, not because the filmmakers actually believed the date to be unlucky.

So, is Friday the 13th actually unlucky? Despite centuries of superstitious behavior, it largely seems like psychological mumbo jumbo. One 1993 study seemed to reveal that, statistically speaking, Friday the 13th is unlucky, but the study's authors told LiveScience that though the data was accurate, "the paper was just a bit of fun and not to be taken seriously." Other studies have shown no correlation between things like increased accidents or injuries and Friday the 13th.

And Friday the 13th isn't a big deal in other cultures, which have their own unlucky days: Greeks and Spanish-speaking countries consider Tuesday the 13th to be the unluckiest day, while Italians steer clear of Friday the 17th. So today, try to rest a little easy—Friday the 13th may not be so unlucky after all.

Additional Source: 13: The Story of the World’s Most Popular Superstition.

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What's the Difference Between Cement and Concrete?

Vladimir Kokorin/iStock via Getty Images
Vladimir Kokorin/iStock via Getty Images

Picture yourself walking down a city block. The sidewalk you follow may be obscured by shuffling feet and discarded gum, but it’s clearly made from something hard, smooth, and gray. What may be less clear is the proper name for that material: Is it concrete or cement? Is there even a real difference between the two words?

Though they’re often used interchangeably, concrete and cement describe different yet related elements of the blocks, flooring, and walls that make up many everyday structures. In simple terms, concrete is the name of the gray, gritty building material used in construction, and cement is an ingredient used in concrete.

Cement is a dry powder mixture that looks much different from the wet stuff poured out of so-called cement trucks. It’s made from minerals that have been crushed up and mixed together. Exactly what kind of minerals it’s made from varies: Limestone and clay are commonly used today, but anything from seashells to volcanic ash is suitable. After the ingredients are mixed together the first time, they’re fired in a kiln at 2642°F to form strong new compounds, then cooled, crushed, and combined again.

Cement
Cement
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This mixture is useless on its own. Before it’s ready to be used in construction projects, the cement must be mixed with water and an aggregate, such as sand, to form a moldable paste. This substance is known as concrete. It fills whatever mold it’s poured into and quickly hardens into a solid, rock-like form, which is partly why it’s become the most widely-used building material on Earth.

So whether you’re etching your initials into a wet sidewalk slab, power-hosing your back patio, or admiring some Brutalist architecture, you’re dealing with concrete. But if you ever happen to be handling a chalky gray powder that hasn’t been mixed with water, cement is the correct label to use.

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Why Do You Stop Feeling Tired As Soon As You Climb Into Bed?

tommaso79/iStock via Getty Images
tommaso79/iStock via Getty Images

There are few situations more frustrating: After a day spent nodding off at your desk, on the train, and on your couch, you suddenly can't sleep the moment you crawl into bed. It's not that you aren't tired or have insomnia, necessarily. Like a curse designed just to torture you, the sleeplessness only seems to occur when you're in your own bed at home, a.k.a. the place where you'd prefer to do your sleeping.

This maddening problem isn't in your head. According to TIME, many people have more trouble falling asleep in their own beds than they do elsewhere thanks to a phenomenon called learned or conditioned arousal. Conditioned arousal develops when you inadvertently train your body to associate your bed with being awake. In many cases, this results from doing stimulating activities in bed. For instance: If you like to slip under the covers and spend 40 minutes watching Netflix before closing your eyes, you're teaching your brain that your bed isn't for sleeping. That means the next time your head hits the pillow, your body will respond by preparing for the next episode of Friends instead of releasing the chemicals that help you fall asleep. The same goes for scrolling through apps, eating, and even reading in bed.

Doing things that aren't sleeping in bed isn't the only way to develop conditioned arousal. If there are other factors keeping you up at night—like thoughts about your day, or that cup of coffee you had at 8 p.m.—they can lead to the same result. Your brain starts to associate being in bed with tossing and turning all night, so even if those mental and physical stimulants go away, the muscle memory of being awake in bed remains.

Conditioned arousal is a vicious cycle that can't be broken in one night. The only way to manage it, according to the American Psychological Association (APA), is to minimize behaviors that contribute to poor sleep habits and to reserve your bed for sleeping (though sex is OK, according to the APA).

If you're a nighttime scroller, browse apps in a different room before getting into bed, or skip checking your phone at the end of the day altogether. When you spend more than 20 minutes struggling to fall asleep in bed, get up and move to a different part of the house until you get sleepy again; this will stop your brain from strengthening the association between your bed and feeling restless. The results won't be instant, but by sticking to a new sleep routine, you should eventually train your body to follow healthier patterns.

Of course, combating conditioned arousal alone isn't always effective. In people with conditions like anxiety and insomnia, intrusive thoughts and genetic factors can prevent them from falling asleep even under ideal circumstances. In such cases, the help of a medical professional may be required to sleep more soundly.

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